The present invention relates to a charged particle beam apparatus that irradiates a charged particle beam onto a sample so as to observe, analyze and process the sample and, in particular, relates to a microfabrication apparatus that implements sample preparation using a mechanical probe, and a probe control method.
Charged particle beam apparatuses for irradiating a charged particle beam onto a sample so as to observe, analyze and process the sample have been widely used in the fields of science and engineering. In recent years, it has been generally carried out to introduce a mechanical probe (hereinafter also referred to as “probe”) into a charged particle beam apparatus, thereby to perform measurement of electrical characteristics of samples, sample preparation, and so on. For example, by combining the focused ion beam technology and the micromanipulation technology, samples in the order of several microns to submicrons can be prepared. This technique is disclosed in JP-A-5-52721 (known example 1).
In the known example 1, a posture of a sample substrate 51 is retained such that an ion beam 52 is irradiated perpendicularly onto the surface of the substrate 51, then the ion beam 52 scans rectangularly in the neighborhood of an observation area 50 to form rectangular holes 54 having a given depth on the surface of the substrate 51 (FIG. 1A). Then, the ion beam 52 scans rectangularly to form a trench 55 on the surface of the substrate 51 (FIG. 1B).
Then, the substrate 51 is inclined such that the axis of the ion beam 52 is inclined by about 30° relative to the surface of the substrate 51, thereby to form an inclined trench 56. The posture change in inclination of the substrate 51 is implemented by a specimen stage (FIG. 1C). The tip of a mechanical probe 53 is brought into contact with a portion of the substrate 51 that becomes a sample (FIG. 1D). Adsorbed gas is supplied from a nozzle for adsorbed gas 20, and the ion beam 52 is irradiated locally onto an area including the tip of the mechanical probe 53, thereby to form an ion beam assisted deposition (hereinafter referred to as “IBAD”) film 57. The tip of the mechanical probe 53 and a sample piece 58 being a separated portion of the substrate 51 in the contacting state are connected to each other by the IBAD film 57 (FIG. 1E). Notching is applied to a residual portion by means of an focused ion beam to cut out the separated sample piece 58 from the substrate 51. The cut-out separated sample piece 58 comes into the state of being supported by the connected mechanical probe 53 (FIG. 1F). The separated sample piece 58 is moved to a required portion, i.e. a sample carrier 59 in this example (FIG. 1G). An IBAD film 60 is formed in an area including the separated sample piece 58 and the sample carrier 59 (FIG. 1H). The observation area 50 in the separated sample piece 58 is formed into a membrane 61 having a thickness of about 100 nm, using an ion beam 52 (FIG. 1I). An electron beam is transmitted through the membrane 61 to carry out observation in transmission electron microscopy.
In this example, no specific explanation is given about a method of restoring or replacing the probe, which is required due to fatigue of the probe caused by extraction of a plurality of separated samples. In practice, by restoring the probe through probe processing using a focused ion beam, or replacing the probe, a plurality of separated samples are extracted using a sample preparing apparatus that combines the focused ion beam technology and the micromanipulation technology.
In the foregoing apparatus that prepares samples by combining the focused ion beam technology and the micromanipulation technology, a probe is fatigued every time probe operations of bonding, cutting off, and fixing a sample are repeated, so that an operator should repeat processing or replacement of a probe per sample preparation. In the conventional apparatus, the operator processes a probe or replaces a probe by taking it out from a sample chamber, relying on an observation image produced by a charged particle beam apparatus. The probe processing is work that requires skill because it is necessary to operate both a probe controller and the charged particle beam apparatus. In such a conventional apparatus, there have been problems to be solved as follows. Specifically, an operator replaces a probe by detaching it from a holder and attaching a new one to the holder using a pincette or the like, while confirming based on eye measurement. Thereupon, if the operator fails in probe replacement, the tip of the probe may be damaged. Further, the number of times that a probe can be restored through the focused ion beam processing without replacement is three to five at most. Therefore, for extracting many samples, the probe replacement should be carried out frequently.